342 Journal of the American Academy of Orthopaedic Surgeons Orthopaedic surgeons increasingly are facing situations that require soft- tissue coverage of lower-extremity defects. Severe open tibial fractures often require coverage of exposed bone fragments with well-vascular- ized tissue, thereby preserving bone viability and reducing the potential for osteomyelitis. After total knee arthroplasty, wound-healing prob- lems may be successfully treated with gastrocnemius flaps. Limb-pre- serving oncologic surgery presents opportunities for creative flaps. However, procedures to gain soft-tis- sue coverage in these and other situ- ations are often referred to surgeons who have more training and experi- ence with such procedures. In the 25 years since Ger 1 popular- ized local muscle flaps to cover soft- tissue defects over the anterior tibia, a multitude of other local and free flaps have been described and per- fected. Complex local flaps and free flaps have greatly expanded limb- salvage indications. Some bone and soft-tissue defects can now be suc- cessfully treated with the bone and soft-tissue transport techniques ini- tially popularized by Ilizarov. Some lower-extremity local flaps offer predictable results and are rel- atively easy to perform. They are not applicable in all situations, and the indications and limitations of each flap must be clearly understood. This review will describe five lower- extremity local flaps that, in our opinion, can be used effectively by orthopaedic surgeons. These flaps were chosen for description because of the relative ease of surgery, relia- bility, and minimal donor-site mor- bidity. However, they are not useful in the region above the ankle and on many areas on the foot. While the dorsalis pedis island flap can be uti- lized in the repair of defects around the ankle, there are many technical pitfalls in its use. Use of a free flap or complex local flap is often neces- sary on the distal part of the lower extremity. General Considerations Flaps are named for the types of tis- sue moved. A muscle flap moves only muscle and often requires a skin graft on the transposed muscle to complete closure of the defect. A musculocutaneous flap transports muscle and skin. The more recently described fasciocutaneous flaps uti- lize the blood supply to the fascia, usually near a deep intermuscular septum, to increase the blood supply to the skin being transported. Direct cutaneous, or axial-pattern, flaps uti- lize subcutaneous arteries and veins in specific body sites to transport Lower-Extremity Local Flaps Gary D. Bos, MD, and Mark J. Buehler, MD Dr. Bos is Associate Professor of Surgery (Orthopaedics), University of North Carolina School of Medicine, Chapel Hill. Dr. Buehler is Assistant Clinical Professor of Surgery (Orthopaedics), Oregon Health Sciences Univer- sity, Portland, and Hand Surgeon, Emanuel Hospital and Medical Center, Portland. Reprint requests: Dr. Bos, Department of Surgery (Orthopaedics), University of North Carolina School of Medicine, Chapel Hill, NC 27599-7055. Copyright 1994 by the American Academy of Orthopaedic Surgeons. Abstract Some soft-tissue defects of the lower extremities can be covered reliably with local flaps. Five such flaps—-the tensor fascia lata, gastrocnemius, soleus, posterior tib- ial artery fasciocutaneous, and dorsalis pedis flaps—-are described. If the indica- tions for each flap are understood and the vascular pedicle is carefully preserved, these flaps can be used to provide relatively simple and reliable coverage of selected soft-tissue defects on the lower extremities. However, the indications must not be overextended in an attempt to avoid a free-tissue transfer. The gastrocnemius flap is most often used. It reliably covers common defects about the knee and the prox- imal tibia. A skin graft is required for the gastrocnemius flap, as well as the soleus flap, which covers the midportion of the tibia. The soleus requires deeper dissec- tion of the calf for elevation. The tensor fascia lata flap and the more recently described posterior tibial artery fasciocutaneous flap are relatively easy to raise, but there are fewer orthopaedic indications for their use. The dorsalis pedis cuta- neous flap is technically more demanding, but it can be used to cover difficult defects around the ankle. J Am Acad Orthop Surg 1994;2:342-351 only cutaneous tissue. A flap trans- porting skin may require a split- thickness skin graft at the donor site for closure. Alterations in the con- tour of the donor site or in the recip- ient bed may lead to an unacceptable cosmetic result. This is particularly true in the thighs of heavy women where cosmetic flap revision may be required at a later date. Mathes and Nahai 2 have provided a useful classification of muscle flaps, although the principles of the classi- fication are often applied to other types of flaps. A type I flap has a sin- gle vascular pedicle and is easiest to transfer. The tensor fascia lata (TFL) and gastrocnemius muscle flaps are examples. The type II flap has one or more dominant pedicles, as well as minor pedicles on the distal end of the muscle, which must be severed to rotate the flap. Occasionally there are problems with vascularity at the end of the flap distant from the major pedicle. Type III (two major pedi- cles), type IV (segmental pedicles), and type V (one dominant and mul- tiple secondary pedicles) flaps have more complex vascular patterns and are not included in this review. This classification points out the necessity of always being aware of the vascular supply of the tissue to be moved. Separation of the major vas- cular pedicle dooms the transfer, as does excessive tension or twisting of the pedicle. When the flap is used for coverage, preservation of the neuro- logic pedicle is unnecessary. 3 In fact, preservation of the neurologic pedi- cle may lead to delayed healing of a skin graft due to movement in the flap. Abnormal sensations may be present, although this has not been a major problem in our experience. When a flap is used to provide cov- erage for an area of insensate broken- down skin, neurologic pedicle preservation may be beneficial, but is beyond the scope of this review. Local flaps rotate about their vas- cular pedicle and not about the ori- gin of the muscle. This characteristic may be used to advantage; for exam- ple, in the gastrocnemius muscle, the origin can be detached from the femur to gain more length. How- ever, the surgeon must always be careful to avoid overestimating the ability of the flap to cover a defect. The vascular pedicle must be kept in mind as the flap is elevated to avoid tension or even disruption of the vessels and failure of the flap. The availability of local flaps is often influenced by associated trauma, par- ticularly in the area of the flap. Crushed tissue or tissue with avulsed or traumatized pedicles will not sur- vive rotation. A preoperative arteri- ogram may be required to document adequate circulation in situations with trauma or previous surgery near the tissue to be transferred. Nearby trauma is especially harmful to fascio- cutaneous flaps that have multiple small perforating vessels through the fascia into the skin. Avulsion of these small vessels during surgery may be prevented by placing temporary sutures at the edge of the flap to hold subcutaneous tissues to the fascia while the flap is being manipulated. Care must also be taken to avoid vas- cular compromise of tissues near the donor site, as in the case of the tunnel under the skin commonly used with gastrocnemius transfer. The area of undamaged skin over a tunnel should be at least 7 cm wide to avoid vascular compromise. Whenever possible, veins should be preserved with the transferred tissue to avoid vascular congestion in the flap. With the excep- tion of the dorsalis pedis island flap, we do not feel that preoperative vas- cular studies are necessary for the flaps described unless there is associ- ated trauma, as noted above. Tensor Fascia Lata Musculocutaneous Flap The TFL musculocutaneous flap is a type I flap consisting of the TFL mus- cle, the fascia lata tendon, and the overlying skin. 4 The pedicle for this flap is the ascending branch of the lat- eral femoral circumflex artery and vein. The flap can be used to cover groin, ischial, trochanteric, and thigh deficits on the lower extremity (Fig. 1). There are many advantages to this flap. It has a reliable blood supply and can be raised easily as a pedicle flap. Potentially, one can raise a large flap extending superiorly from the anterior superior iliac spine to 10 cm above the knee and from the midline anteriorly to the midline posteriorly. However, most flaps are smaller and do not extend closer than 15 cm above the knee. The TFL functions as an accessory hip flexor, hip abductor, and internal rotator of the thigh. It is not the primary muscle for any of these functions, making it function- ally expendable. A sensory myocu- taneous flap can be constructed if the limitations in size described by Strauch and Yu 5 are followed. The sensory TFL flap is not described in this review. Vol 2, No 6, Nov/Dec 1994 343 Gary D. Bos, MD, and Mark J. Buehler, MD Fig. 1 Potential areas of coverage available with the TFL flap. The end of the flap can be as close as 10 cm, but is preferably 15 cm, from the knee-joint line. There are some disadvantages with this pedicle flap. The sec- ondary defect in the thigh may not close primarily if the width of the TFL flap exceeds 6 cm in a patient with normal habitus. Therefore, a split-thickness skin graft will be required for closure. In the thin male patient this is not a major cosmetic problem, but in a woman with heavy thighs a significant contour defect results. In addition, in heavy patients the thickness of the flap may necessitate later surgery to recon- tour and thin the transported flap. Another disadvantage results from the fascia lata itself, which comprises the undersurface of the distal half of the flap. This fascia is stiff and does not fold well over con- cave surfaces or tuck well into deep holes. Also, the fascia lata does not adhere well to the underlying defect, and in contaminated wounds the potential dead space between the flap and the wound can be a source of hematoma or abscess. In patients with surgical scars in this area, this flap should not be attempted unless an arteriogram documents patency of the pedicle, because the vascular pedicle to the flap is often severed in the routine anterior or anterolateral surgical approach to the hip. Anatomy The TFL muscle arises from the ilium between the origin of the glu- teus minimus and the anterior part of the iliac crest. 6 The muscle lies between the laminae of the iliotibial tract and inserts into the tract just below the level of the greater trochanter. The muscle is about 5 cm wide. Its posterior border runs from a point 5 cm posterior to the anterior superior iliac spine down to the ilio- tibial tract, passing just anterior to the greater trochanter. The surface marking of the muscle is easily demonstrated by having the supine patient elevate the leg with the knee extended. The muscle stands out readily, and the axis of any proposed flap should be marked preopera- tively along the course of the demonstrated muscle. The arterial supply is from the ascending branch of the lateral femoral circumflex artery, which is usually a branch of the deep femoral artery. This 2-mm-diameter vessel passes laterally deep to the sartorius and rectus femoris muscles, under which it divides into ascending and descend- ing branches. The ascending branch courses along the intertrochanteric line at the site of origin of the vastus inter- medius and lateralis muscles under cover of the rectus femoris. Here it enters the TFL muscle on its deep sur- face at the level of the greater trochanter (Fig. 2). Flap Elevation The flap usually measures 8 to 12 cm in width and is always centered over the muscle with the upper bor- der being the iliac crest. Flaps can be raised to a length of about 30 cm or to within 10 cm, but preferably 15 cm, from the knee joint. Usually the cutaneous anterior boundary of the TFL flap is defined by a line from the anterior superior iliac spine to the lateral femoral condyle, but it can extend as far as the midline of the thigh. The posterior border follows a line from the posterior edge of the greater trochanter to the center of the lateral femoral condyle, although a wider flap extending to the edge of the biceps femoris muscle can be designed. The dissection is started inferiorly with an incision through the skin and fascia onto the vastus lateralis muscle. The fascia is sutured to the skin to avoid shearing of the skin from the underlying fascia. The anterior and posterior margins are incised, and the flap is elevated from distal to proximal by using blunt fin- ger dissection to gently separate the fascia from the underlying vastus lateralis. The posterior incision can be safely extended to the iliac crest to help mobilize the flap, since the pedicle enters on the anterior bor- der. Proximally, the anterior inci- sion should stop about 10 cm below the anterior superior iliac spine, as this is where the vascular pedicle is located (Fig. 2). Exposure of the pedicle is not necessary unless a greater degree of mobilization is needed for flap transposition. The flap is then transposed to cover the defect. The sutures placed previously to avoid shear- ing are removed, and the flap is sutured in place. During transposi- tion and insetting, the color of the flap and bleeding from the edge of the flap must be watched closely. The pedicle can become kinked, leading to insufficient arterial inflow manifested by pale color or lack of bleeding. Occlusion of the 344 Journal of the American Academy of Orthopaedic Surgeons Lower-Extremity Local Flaps Fig. 2 Outline of a typical TFL flap. A wider flap would necessitate a skin graft for closure of the donor site. The TFL muscle area is shaded. draining veins may make the flap appear dark and congested with excess bleeding. In either case, the flap must be taken down immedi- ately, and the pedicle must be explored and mobilized to restore patency. The donor site is closed primarily if possible, or a split- thickness skin graft is applied. Gastrocnemius Muscle Flap Skin-grafted medial or lateral gas- trocnemius muscle flaps are the workhorse local transposition flaps for soft-tissue coverage of the knee and the proximal third of the tibia (Fig. 3). 7 Either or both of these type I muscle flaps can be raised by a sur- geon with a basic understanding of the anatomy of the posterior com- partment of the leg. Although the gastrocnemius is the largest muscle of the posterior leg compartment, the actual size of the muscle varies greatly depending on the patient’s habitus. The surgeon must try to determine preopera- tively if the bulk of gastrocnemius muscle is adequate to cover the wound defect. In a young trauma patient the muscle is usually well developed. However, in the elderly patient who has undergone total knee arthroplasty and who has a wound dehiscence, it may be quite small. If the patient has well-devel- oped calves and muscular legs, a large gastrocnemius muscle will be present. If the patient has long, thin legs or is malnourished with poor muscle development, the muscle will have little bulk and will supply poor coverage. The bulk of the transferred gastrocnemius muscle is occasionally a source of cosmetic complaint by patients. A musculocutaneous gastrocne- mius flap can be used to increase flap length. The extended length adds only cutaneous tissue and requires a split-thickness skin graft to close the donor site. The cosmetic result may be unacceptable due to the donor-site contour defect. The musculocutaneous gastrocnemius flap is not described in this review. The superficial posterior location of the muscle allows relative ease of elevation of the flaps. This location also protects the muscle from dam- age in most injuries, since wounds are more often anterior over the sub- cutaneous border of the tibia. One exception is the crushing injury (e.g., a bumper injury) in which the poste- rior muscles have been damaged. In this situation, the gastrocnemius muscle may be unfit for local trans- position, and a free flap may be required. Anatomy The medial and lateral heads of the gastrocnemius muscle take ori- gin from their respective femoral condyles and join just distal to the knee. The muscle becomes tendi- nous near the junction of the middle and distal thirds of the leg and joins the soleus tendon to form the Achilles tendon. The medial head is larger and longer (3.0 to 4.0 cm) than the lateral head and is the preferred head of the gastrocnemius for local transposition flaps if allowed by the location of the defect. The medial head is adjacent to the tibia, allowing the muscle to be easily transposed over the typical proximal anterior tibial wound as far as the lateral border of the patella. The lateral head is separated from the tibia by the fibula, the lateral compartment, and the anterior com- partment, making the reach to the tibia longer. Even so, it can easily reach the lateral border of the patella. If it is necessary to gain additional length, the lateral head can be tun- neled under the lateral and anterior compartments after a fibulectomy to decrease the distance to the defect. This must be done with extreme care so that the pedicle to the muscle does not become kinked under the ante- rior and lateral compartments. Fibulectomy can lead to other prob- lems. For example, it may preclude later reconstructive procedures, such as fibula-to-tibia grafts to achieve fracture union. Because the sural artery is the sin- gle proximal dominant vascular pedicle to each head of the muscle, the gastrocnemius muscle flap is a type I flap. Each head has a separate sural artery, which is a branch of the popliteal artery at the level of the femoral condyle. Each artery enters the muscle just beneath the level of the joint space and arborizes in the proximal muscle. It supplies the skin over the muscle and distal to the mus- cle belly through a fasciocutaneous circulation. The blood supply is very reliable unless there has been a knee dislocation or a significantly dis- placed supracondylar femoral frac- ture. These injuries can result in damage to the sural arteries, render- ing the gastrocnemius nonviable if raised on this pedicle. A similar situ- ation may exist if the patient has had a femoral popliteal vascular bypass Vol 2, No 6, Nov/Dec 1994 345 Gary D. Bos, MD, and Mark J. Buehler, MD Fig. 3 Areas of potential anterior coverage from medial and lateral gastrocnemius mus- cle flaps. because of either trauma or periph- eral vascular disease. If that is the case, an arteriogram must be obtained to document patency of the sural arteries before a local gastrocne- mius transposition flap is attempted. Flap Elevation Medial Gastrocnemius Muscle Flap The muscle is exposed using a lon- gitudinal incision that parallels the medial border of the tibia. 8 If the flap is to be tunneled under a skin bridge, the incision is placed posteri- orly so that the bipedicle flap created between the incision and the ante- rior defect is at least 7 cm in width. This is necessary to prevent skin necrosis when this bridge of skin is raised to allow transposition of the muscle under the skin bridge and into the anterior wound (Fig. 4). The incision extends from the tibial plateau to 8 to 10 cm above the ankle. The saphenous vein should be left attached to the superficial fascia to maintain maximum venous outflow from the damaged leg. The muscle is easily separated from the overlying subcutaneous tis- sue and fascia by blunt dissection. The plane between the soleus and the medial head of gastrocnemius is developed with finger dissection. The location of the few small vessels in this interval should be noted before they are carefully coagulated, since they may help define the loca- tion of the median raphe. The medial head is then separated from the lateral head by identifying the raphe between them. This raphe is difficult to see in well-developed individuals, but there are other clues to the proper line of separation. On the superficial posterior surface of the gastrocnemius muscle, the inter- val is defined by the sural nerve. On the deep surface of the gastrocne- mius, multiple small vessels connect the soleus to the gastrocnemius in a longitudinal fashion along the raphe. This anatomic feature helps define the interval. Proximally, the raphe may be defined by careful fin- ger dissection into the popliteal fossa where the two heads separate. The attachment of the medial head to the Achilles tendon is sharply released, leaving a small amount of tendon still attached to the muscle for later suture placement. The two heads are then separated using sharp and blunt dissection. As the dissection approaches the knee joint, finger dissection is preferred to avoid damage to the sural vessels. The bridge of skin and subcutaneous tissue separating the traumatic wound and the incision is raised, making sure that there is adequate space to avoid pressure on the trans- posed muscle. If the width of the flap is inade- quate, the deep fascia of the muscle can be removed or incised longitudi- nally to allow the muscle to spread out and cover more area. The small amount of tendon on the distal end of the muscle is used to set the flap into the defect. If the medial head does not reach the wound, it can be further mobilized by releasing the muscle from its origin on the medial femoral condyle, taking care to preserve the vascular pedicle, which enters the muscle about 3 cm above the joint line. The flap can be inverted if nec- essary for better coverage or contour. It is then grafted with a meshed split- thickness skin graft. If the exposed fascia on the flap is thick, it can be carefully stripped from the flap, or multiple small incisions can be made in the fascia (“pie-crusting”) for bet- ter take of the skin graft. Wounds are closed over suction drains. Lateral Gastrocnemius Muscle Flap To mobilize the lateral head, a lon- gitudinal incision is made 2 or 3 cm posterior to the fibula. The incision may have to be placed more posteri- orly to allow for an adequate width of skin between the anterolateral defect and the posterolateral longi- tudinal incision if a tunnel is to be used. The peroneal nerve is identi- fied at the neck of the fibula and is protected throughout the dissection. The skin is separated from the mus- cle, and the lateral head is separated from the medial as previously described. The muscle is then trans- posed into position, often under the mobilized bridge of skin. The per- oneal nerve is again checked to avoid possible tension on the nerve by the transposed muscle. The mus- cle is skin-grafted, and the wound is closed as previously described. Soleus Muscle Flap The soleus muscle flap is second only to the gastrocnemius flap as a local flap for soft-tissue coverage of 346 Journal of the American Academy of Orthopaedic Surgeons Lower-Extremity Local Flaps Fig. 4 Completed medial gastrocnemius flap performed by using a subcutaneous tun- nel with a minimum of 7 cm between the incision and the defect. Flap area is shaded. the tibia. This type II flap is the pre- ferred local flap for coverage of the middle third of the tibia (Fig. 5). The soleus is expendable, especially when transferred as a “hemisoleus,” and harvest leaves a very subtle donor-site deformity. 9 However, this flap is more difficult to raise than the gastrocnemius flap because attention must be paid to the adja- cent posterior tibial neurovascular bundle. A significant disadvantage of the soleus flap is that circulation to the distal end of the flap is unreli- able. This is especially true in the case of a high-energy fracture. Although the soleus occupies the posterior compartment of the leg with the gastrocnemius, it is affected differently in many open fractures. Since the soleus is closely adherent to the deep posterior surface of the interosseous membrane and the tibia and fibula, it is often damaged in open high-energy or crush fractures of the tibia. The resultant muscle injury is often severe enough to pre- clude its use as a transposition flap. Judgment is key in selecting reli- able soleus transposition flaps. If the preoperative evaluation shows a great deal of ecchymosis and swelling in the posterior compartment and there is gross instability of the frac- ture, one can assume significant frac- ture displacement and damage to the soleus. If the initial radiographs, especially the lateral view, show gross displacement of the fracture, poste- rior-compartment muscle damage is likely. During the initial debridement of the wound, digital exploration will occasionally reveal penetration of the soleus by the fractured tibia, making the muscle unsuitable for transposi- tion. In these situations, free-tissue transfer is a better choice for middle- third tibial coverage. Anatomy The soleus is a muscle of the superficial posterior compartment of the leg and is located deep to the gastrocnemius muscle. It extends the entire length and width of the leg. Unlike the gastrocnemius, which has no direct origin on the tibia, the soleus originates from the posterior surface of the tibia, the interosseous membrane, and the proximal third of the fibula. The muscle joins with the gastrocnemius and inserts into the calcaneus. In the proximal third of the leg, it is cov- ered by the belly of the gastrocne- mius; in the middle third, it is located beneath the tendon of the gastrocnemius; and in the distal third, it blends with the tendon of the gastrocnemius. The soleus is a bipenniform muscle. The medial head originates from the posterior surface of the tibia. The lat- eral head originates from the proxi- mal fibula. The medial and lateral heads are fused proximally, and in their distal half they are separated by a well-defined septum before they fuse with the gastrocnemius tendon. The soleus is considered to have a type II pattern of blood supply, with the popliteal, posterior tibial, and per- oneal arteries giving dominant branches to the proximal third of the two heads of the muscle. The lateral head receives most of its blood supply from the peroneal artery. The distal two thirds of the muscle receives minor pedicles from the posterior tibial artery (PTA). These branches must be sev- ered before flap rotation, and their loss may account for the occasional under- perfusion of the distal portion of the flap. The surgeon must closely observe the distal flap circulation before the flap is sutured into position. 8 Flap Elevation Under tourniquet control, the soleus is harvested by means of a medial approach through a longitudi- nal incision paralleling the border of the tibia and extending from just beneath the tibial plateau to just above the medial malleolus. If possible, this incision should incorporate the trau- matic wound to avoid creating a skin bridge. Either a hemisoleus or a total soleus flap can be elevated, depending on the size of the traumatic defect and the size of the soleus. If a medial hemisoleus flap is raised, one must split the soleus lateral to the midline to capture the intermuscular artery, which runs down the center of the muscle. This will increase the likeli- hood of survival of the entire muscle. If, for some uncommon reason, the lateral approach is used to har- vest a soleus flap, the surgeon must be aware that the fibula will limit the arc of rotation. This can be corrected somewhat by removal of the fibula, but it must be accepted that this could lead to problems with late reconstruction of a tibial nonunion. Ordinarily, the soleus is identified in the proximal third of the leg, where it lies between the gastrocnemius muscle and the deep transverse fascia. The posterior tibial neurovascular bundle is identified and protected. After the muscle has been cleared on both its deep and its superficial surface, it is separated from the Achilles tendon. The width of the harvested muscle is Vol 2, No 6, Nov/Dec 1994 347 Gary D. Bos, MD, and Mark J. Buehler, MD Fig. 5 Areas of potential anterior coverage from medial and lateral transposition of the soleus muscle. Transposition around the lat- eral side is seldom used. dictated by the defect. Distal small perforators from the posterior tibial vessels are ligated and divided as nec- essary to allow flap rotation. The flap is rotated into the defect and inset. It is then covered with a meshed split- thickness skin graft, and the incision is closed in standard fashion, using a drain if necessary. Posterior Tibial Artery Fasciocutaneous Flap Prior to the introduction of local transposition muscle flaps and microvascular free-tissue transfers, random cutaneous flaps were attempted for soft-tissue coverage in the leg with mixed success. In 1981, Pontén 10 pointed out the signifi- cance of the fasciocutaneous circula- tion. Subsequently, the vascular anatomy of the skin was closely detailed. 11 Fasciocutaneous flaps were designed with more pre- dictable circulation, and acceptable results were reported. 12,13 There are some disadvantages to the fasciocutaneous flap. Unlike mus- cle flaps, the fasciocutaneous flap has minimal bulk and cannot be used to obliterate dead space in a wound. The skin flap has less blood supply than a muscle flap, which decreases its abil- ity to resist the contamination often seen in these defects. If the flap is not carefully designed, tip necrosis may result, compromising coverage of the defect. Many high-energy and crush- ing injuries damage the fasciocuta- neous envelope to a degree that contraindicates its use. Patients with diabetes mellitus or peripheral vascu- lar disease and elderly patients are generally not candidates for fasciocu- taneous flaps. In spite of these disadvantages, the PTA fasciocutaneous flap may be successfully applied to some small middle-third and distal-third tibial soft-tissue defects (Fig. 6), provided the defect is at least 10 cm from the ankle. The flap is easy to raise if the principles of fasciocutaneous circu- lation are applied. Open fractures associated with low-energy injuries and minimal muscle or bone loss are ideal indications. These situations are uncommon but are sometimes seen in fractures associated with an abrasive action. An example is trauma due to striking the leg on the dashboard in a motor-vehicle acci- dent and avulsing the pretibial skin, with or without associated tibial fracture. This is a low-energy injury with exposed bone, but the sur- rounding fasciocutaneous envelope is in good condition, allowing for a local fasciocutaneous transposition flap. The PTA fasciocutaneous flap can be rotated farther than the com- monly used bipedicle (“relaxing incision”) flap in this situation. Anatomy The fasciocutaneous perforators of the posteromedial aspect of the leg arise from the PTA. Arterial and venous perforators from the PTA course to the skin through the crural septum between the deep and superficial muscle compartments of the posterior portion of the leg. The skin flap is dependent on these sep- tal perforators for survival. The PTA gives off a series of five or six perfo- rators, which emerge in the crural septum between the soleus and the flexor digitorum longus muscle. They perforate the fascia and con- nect to a plexus at the level of the deep fascia. The lowest perforators are 5 to 7 cm above the malleolus. Flap Elevation The flap design is dictated by the defect. Usually, a tongue-shaped flap is fashioned with the flap based proximally and with a maximum length-width ratio of 3:1. The saphe- nous vein is always included in the flap to aid in venous outflow (Fig. 7). The posterior incision is made in such a fashion as to avoid exposure of the Achilles tendon after transpo- sition. The distal portion of the flap should not extend closer to the malleolus than 2 or 3 cm. After rota- tion, the flap will not cover defects closer to the ankle than 10 cm. The incisions are carried through the skin, fat, and deep fascia. Sutures 348 Journal of the American Academy of Orthopaedic Surgeons Lower-Extremity Local Flaps Fig. 6 Area of potential anterior coverage with a PTA fasciocutaneous flap. Fig. 7 Outline of a typical PTA fasciocuta- neous flap. The long saphenous vein is divided at the distal end of the flap and transposed with the flap. Flap area is shaded. are placed in the flap to prevent shearing between the skin and the fascia during manipulation. Once the skin and fascia have been incised, the posterior aspect of the flap can be elevated with fin- ger dissection because only loose alveolar tissue connects the fascio- cutaneous flap to the muscles pos- teriorly. The septum between the deep and superficial compart- ments of the leg tethers the flap at this point and must be released to allow adequate mobility of the flap. Since this septum contains the septal perforators, it must be released judiciously to allow ade- quate release for wound coverage. Occasionally, the perforators can be visualized in the septum and can be spared by releasing the fas- cia without cutting the vessels. The flap is then transposed over the bone, and the resultant defect in the posteromedial portion of the leg is closed with a meshed split-thick- ness skin graft. Any unsightly dog- ear created by rotation of the flap should be revised after healing is complete to avoid vascular compro- mise to the flap. Dorsalis Pedis Island Flap Many skin flaps that were once thought to have direct axial blood supply are now thought to be sup- plied by the fasciocutaneous system. However, the dorsalis pedis island flap remains an example of a direct axial flap. Careful attention to detail is required to successfully raise this skin flap, which relies on a single inflow artery. This is a good local flap for coverage of ankle and hind- foot skin defects (Fig. 8), 14,15 but it is the most technically demanding of the flaps discussed in this review. Care must be taken to achieve good donor-site coverage with a skin graft because of the location on the dor- sum of the foot. Anatomy The anterior tibial artery supplies the dorsum of the foot as it crosses the ankle and continues as the dor- salis pedis artery. Venous outflow from this flap is via the venae comi- tantes and the long saphenous vein. The dorsalis pedis artery runs along the tarsus to the first intermetatarsal space, where it gives off a branch to the plantar surface and then contin- ues as a nondominant supply to the first and second toes (Fig. 9). The cutaneous branches of the dorsalis pedis artery enter the skin in a fairly small strip extending from the exten- sor retinaculum to a point halfway along the first interosseous space. Beyond this point the skin is sup- plied by the first dorsal metatarsal artery (FDMA), a continuation of the dorsalis pedis artery, which lies beneath the tendon of the extensor hallucis brevis muscle. The origin of the FDMA is crucial to the supply of the distal part of the flap. In as many as 20% of patients, the FDMA has a plantar origin instead of arising from the dorsalis pedis artery. This precludes its use in a local rotation flap, since the arc of rotation is significantly shortened. Also, in the older patient the dorsalis pedis artery can be atherosclerotic, which is another contraindication to use of this flap. In most cases an arteriogram should be obtained pre- operatively to evaluate these poten- tial problems and to ensure that the PTA is patent into the foot. Flap Elevation The shape of the flap is dictated by the defect, although some guidelines are helpful. 16 Most of the vascular- ization of the flap comes from the proximal portion of the FDMA. The design of the flap should be such that the central portion overlies this area when possible. A venous tourniquet should be placed on the leg prior to dissection to mark the long saphenous vein and the dor- salis pedis artery. This will allow easy incorporation of the long saphenous vein into the flap. The dorsalis pedis artery should be used as the axis of the flap. The proximal margin of the flap is at the lower border of the extensor retinaculum. The flap can extend across the width of the dorsum of the foot but should not pass around the borders of the foot. Distally, the inci- sion is made proximal to the web spaces of the toes. Much of the blood supply to the distal part of the flap comes from the FDMA, and the vari- able arrangement of this vessel may determine the tendency for marginal necrosis at the distal end. For this reason, the flap is seldom larger than 10 × 10 cm. After the flap design has been drawn on the dorsum of the foot, using the dorsalis pedis artery as the axis, and the long saphenous vein has been included, the venous tourniquet is released. The distal incision is made first so that the FDMA can be identi- fied. If it is not present or is deep and atrophic, the procedure should be aborted, and free-tissue transfer should be elected. It is important to develop a plane that leaves sufficient peritenon for take of the split-thick- ness skin graft on the extensor ten- dons. This step is very important because incomplete take of the split- thickness skin graft on the tendons is the major complication with this flap. Vol 2, No 6, Nov/Dec 1994 349 Gary D. Bos, MD, and Mark J. Buehler, MD Fig. 8 Areas of potential coverage from the dorsalis pedis island flap. 350 Journal of the American Academy of Orthopaedic Surgeons Lower-Extremity Local Flaps The distal end of the flap is then raised, and the FDMA is identified, divided, and sutured to the distal edge of the flap to prevent shearing between the flap and the vessels, which would cause devasculariza- tion. At this point, the flap must be checked for adequate perfusion. If the distal part of the proposed flap is dusky, the incision should be closed, and a free flap should be selected to fill the defect. If vascularity is intact, the incision is extended up the medial border of the flap, with care being taken not to damage the long saphe- nous vein but to take it with the flap. As the medial edge of the flap is raised, the tendon of the extensor hallucis longus will be noted. The dissection is continued superficial to this tendon. The vessels are then raised with the flap from distal and lateral to proximal and medial, always watching the vessels to make sure that they are included with the flap. The extensor hallucis brevis tendon must be divided to raise the flap, since the vessel runs deep to the tendon (Fig. 9). The plantar communicating artery will be encountered between the bases of the first and second metatarsals; this must be ligated to raise the flap. The proximal skin incision is made, and mobilization of the flap is completed. A more proximal longitudinal incision may be necessary to mobi- lize more of the vessel, extending the length of the pedicle. To accomplish this, the extensor retinaculum is cut, and the extensor tendons are retracted, exposing the dorsalis pedis artery and the anterior tibial vessels. During the dissection, the exposed extensor tendons must be kept moist to avoid damage to the peritenon, which might compromise take of the skin graft. The flap is sutured into position, and a minimally meshed split-thickness skin graft is placed on the donor site. The pedicle must be inspected again to make sure that kinking did not occur. The foot is dressed with a bolster and is splinted for at least 2 weeks to maxi- mize incorporation of the skin graft. Summary Of the five lower-extremity local flaps discussed, the gastrocnemius flap is used most often because it covers wounds at the knee and prox- imal tibia, which are the common sites of defects. This flap is relatively easy to use and has predictably good results. The TFL and PTA fasciocu- taneous flaps are also easy to use if the vascular anatomy is respected, but there are relatively few orthopaedic indications for these flaps. The soleus and dorsalis pedis flaps are the most technically demanding of the five flaps. The contraindications and caveats men- tioned must be observed for the flaps to be successful. Fortunately, free-flap techniques and more com- plex local flaps are available in most situations if the described local flaps will not work, as is the case in the area proximal to the ankle and in many areas on the foot. Fig. 9 Anatomic details of the dorsalis pedis artery and its extension as the first dorsal metatarsal artery. Vol 2, No 6, Nov/Dec 1994 351 Gary D. Bos, MD, and Mark J. Buehler, MD References 1. Ger R: The management of pretibial skin loss. Surgery 1968;63:757-763. 2. Mathes SJ, Nahai F: Vascular anatomy of muscle: Classification and applica- tion, in Mathes SJ, Nahai F (eds): Clinical Applications for Muscle and Muscu- locutaneous Flaps. St Louis: CV Mosby Company, 1982, pp 20-26. 3. Pico R, Lüscher NJ, Rometsch M, et al: Why the denervated gastrocnemius muscle flap should be encouraged. Ann Plast Surg 1991;26:312-324. 4. McCraw JB, Arnold PG: Tensor fascia lata, in McCraw JB, Arnold PG (eds): McCraw and Arnold’s Atlas of Muscle and Musculocutaneous Flaps. Norfolk, Va: Hampton Press Publishing Company, 1986, pp 423-443. 5. Strauch B, Yu HL: Tensor fascia lata flap, in Strauch B, Yu HL (eds): Atlas of Micro- vascular Surgery: Anatomy and Operative Approaches. New York: Thieme Medical Publishers, 1993, pp 174-179. 6. Cormack GC, Lamberty BGH: Lateral circumflex femoral artery, in Cor- mack GC, Lamberty BGH (eds): The Arterial Anatomy of Skin Flaps. Edin- burgh: Churchill Livingstone, 1986, pp 317-319. 7. Mathes SJ, Vasconez LO: Lower extrem- ity reconstruction, in Mathes SJ, Nahai F (eds): Clinical Applications for Muscle and Musculocutaneous Flaps. St Louis: CV Mosby Company, 1982, pp 542-553. 8. Yaremchuk MJ, Manson PN: Local and free flap donor sites for lower-extremity reconstruction, in Yaremchuk MJ, Burgess AR, Brumback RJ (eds): Lower Extremity Salvage and Reconstruction: Orthopedic and Plastic Surgical Manage- ment. New York: Elsevier Science, 1989, pp 118-132. 9. Tobin GR: Hemisoleus and reversed hemisoleus flaps. Plast Reconstr Surg 1985;76:87-96. 10. Pontén B: The fasciocutaneous flap: Its use in soft tissue defects of the lower leg. Br J Plast Surg 1981;34:215-220. 11. Cormack GC, Lamberty BGH: The anatomical basis for fasciocutaneous flaps, in Hallock GG (ed): Fasciocuta- neous Flaps. Boston: Blackwell Scientific Publications, 1992, pp 13-24. 12. Fix RJ, Vasconez LO: Fasciocuta- neous flaps in reconstruction of the lower extremity. Clin Plast Surg 1991;18: 571-582. 13. Louton RB, Harley RA, Hagerty RC: A fasciocutaneous transposition flap for coverage of defects of the lower extrem- ity. J Bone Joint Surg Am 1989;71: 988-994. 14. McCraw JB, Furlow LT Jr: The dorsalis pedis arterialized flap: A clinical study. Plast Reconstr Surg 1975;55:177-185. 15. Kamal MS, Azab AS, Talaat HA: Leg repairs with an island flap from the dor- sum of the foot, based on the anterior tibial vessels. Plast Reconstr Surg 1979;64: 498-504. 16. Cormack GC, Lamberty BG: Dorsalis pedis artery, in Cormack GC, Lamberty BG (eds): The Arterial Anatomy of Skin Flaps. Edinburgh: Churchill Livingstone, 1986, pp 279-281. . branch of the lat- eral femoral circumflex artery and vein. The flap can be used to cover groin, ischial, trochanteric, and thigh deficits on the lower extremity (Fig. 1). There are many advantages. the junction of the middle and distal thirds of the leg and joins the soleus tendon to form the Achilles tendon. The medial head is larger and longer (3.0 to 4.0 cm) than the lateral head and is. For example, it may preclude later reconstructive procedures, such as fibula-to-tibia grafts to achieve fracture union. Because the sural artery is the sin- gle proximal dominant vascular pedicle